Reverend Toller is a true believer who carries out his duties with an earnestness that belies the profound cost to his health and happiness. He is as much a lonely lighthouse keeper as a holy man.

Director Paul Schrader has been tending his own flame in relative solitude for years now. He’s one of the last holdouts from his generation of iconoclastic ’70s filmmakers. Ashby, Altman, and Nichols are dead. Francis Ford Coppola makes wine, Peter Bogdanovich has gone to seed, and Martin Scorsese has been (rightfully) nominated for sainthood.

Schrader never veered from his thorny path. The vogue for his hyper-aggressive explorations of suffering and nihilism came, went, came back, and went again, but he’s still here. This despite coming off a grueling trio of features that includes two Nic Cage duds plus the cheap and sleazy, Lindsay Lohan-starring Bret Easton Ellis collaboration The Canyons.

But First Reformed is his best work since 2002’s Auto Focus. And the grim, lurid Schraderisms come fast here.

The pregnant Mary (Amanda Seyfried) summons Toller to speak with her husband, Michael (Philip Ettinger), recently released from a prison stint for his environmental activism. Radicalized Michael believes the only moral choice in the era of climate change is to kill his new baby as soon as it’s born. He’s also considering more violent options.

Toller is a stand-in for Schrader here, speaking to his younger self. Time and tragedy have granted him wisdom he struggles to impart to a young, hotheaded revolutionary thinking in absolutes.

Their philosophical debates invigorate Toller, who has blunted his passions against the cold stone of an ascetic lifestyle. Tragedy drove him away from society, but in environmental extremism he sees the possibility for a greater expression of real holiness.

Or maybe he’s come unhinged.

For all its fervid musings, First Reformed is more sober reflection than screed. Schrader ponders Kierkegaard and Thomas Merton, giving consideration to several sides of the argument.

Toller’s house of worship is but a relic of an outpost for a 5,000-seat megachurch run by charismatic minister Jeffers (Cedric “The Entertainer” Kyles). But Schrader doesn’t indulge in straw men here. Though he’s clearly aligned with Toller’s tiny parish, Schrader doesn’t paint Jeffers in slickster clichés, and the character benefits from a terrific performance by Kyles, who holds his own with a never-better Hawke.

This is still Paul Schrader, so some hyperbole is expected. There’s the unsubtle contrast of Toller delivering a communion of wafers gracefully dipped in wine, followed by his solitary alcoholic dinner of a hunk of bread dunked into a bowl of whiskey. And a pregnant Christian girl named Mary? A bit on the nose.

But mostly this is thoughtful, compelling stuff that recalls Schrader’s similar New England-set slow-motion freakout, Affliction. And Toller’s drive through the banal poverty of a skid-row street is an intentionally hollow echo of Taxi Driver’s Stygian sojourns through ’70s-era NYC.

Schrader remains a true believer. His unflinching, thoughtful explorations of a bleak worldview will almost certainly drive some audiences away from First Reformed, but such is the lonely life of a lighthouse keeper.